package 编程题3;

import java.util.Map;

public class Circle {
    private  double  r;

    public void setR(double r) {
        this.r = r;
    }

    public Circle(double r) {
        this.r = r;
    }

    public Circle() {
    }
    public   double getArea(double  r){
        double  s= Math.PI*r*r;
        System.out.println(s);
        return   s;
    }
}
